The conventional surface protective layer and interlayer insulating layer for a semiconductor device includes a polyimide resin which can have excellent heat resistance, electrical characteristics, mechanical characteristics, and the like.
The polyimide resin has recently been used as a photosensitive polyimide precursor composition which can be coated easily. The photosensitive polyimide precursor composition is coated on a semiconductor device, patterned by ultraviolet (UV) rays, developed, and heat imidized, to easily provide a surface protective layer, an interlayer insulating layer, and the like.
Accordingly, it is possible to significantly shorten the processing time compared with that of a conventional non-photosensitive polyimide precursor composition.
The photosensitive polyimide precursor composition can be applied as a positive type in which an exposed part is dissolved by development, or a negative type in which the exposed part is cured and maintained. Positive type compositions can be developed by a non-toxic alkali aqueous solution.
The positive photosensitive polyimide precursor composition can include a polyimide precursor of polyamic acid, a photosensitive material of diazonaphthoquinone, and the like. However, it can be difficult to obtain a desired pattern using the positive photosensitive polyimide precursor composition because the carbonic acid of the polyamic acid is too highly soluble in an alkali.
In order to solve this problem, a material to which a phenolic hydroxyl acid has been introduced instead of carbonic acid by esterifying polyamic acid with an alcohol compound having at least one hydroxyl group has been proposed, but this material is insufficiently developed, causing problems of layer loss or resin delamination from the substrate.
Recently, a material in which a polybenzoxazole precursor is mixed with a diazonaphthoquinone compound has drawn attention, but when the polybenzoxazole precursor composition is actually used, layer loss of an unexposed part can be significantly increased, so it is difficult to obtain a desirable pattern after the developing process.
In order to improve this, if the molecular weight of the polybenzoxazole precursor is increased, the layer loss amount of the unexposed part is reduced, but development residue (scum) is generated, so resolution may be decreased and the development duration on the exposed part may be increased.
In order to solve this problem, layer loss may be suppressed in non-exposed parts during development by adding a certain phenol compound to a polybenzoxazole precursor composition. However, the effect of suppressing the layer loss of the unexposed part is insufficient. Accordingly, there is still a need to increase the effects on suppressing layer loss, along with preventing generation of development residue (scum).
In addition, since the phenol for controlling solubility may decompose or participate in side reactions at a high temperature during thermosetting, which can significantly damage the mechanical properties of the resultant cured layer, there is still a need for a substitute for the dissolution controlling agent. In addition, there is a need to improve sensitivity in order to improve the productivity of electronic devices along with maintaining a similar or improved level of optical properties such as resolution as compared to conventional materials.